A study on the correlation between body mass index and peak expiratory flow rate in school-going children aged between 8 and 12 years

Background: Peak expiratory flow rate (PEFR) is a simple indicator of lung function in children and may be influenced by growth, nutritional status, and environmental exposures. Understanding these associations aids in the early recognition of impaired respiratory health. Aims and Objectives: This study aimed to evaluate the correlation between body mass index (BMI) and PEFR in school-going children aged 8–12 years. Materials and Methods: A cross-sectional study was conducted among school children aged 8–12 years attending a school attached to a tertiary care teaching hospital in India in the Department of Paediatrics, Government Salem Medical College, Salem, over a period of 1 year. Anthropometric measurements were recorded, BMI was classified using the World Health Organization standards, and PEFR was measured using a standardized peak flow meter. PEFR was the primary outcome, and associations were analyzed using correlation and multivariable regression analyses. Results: The mean age of participants was 9.5±0.79 years, with equal pre-adolescents (50.1%) and early adolescents (49.9%). Boys constituted 54.2% of participants, with a mean weight of 30.2±7.8 kg and a mean height of 132.7±7.7 cm. Most children had normal BMI (61.1%), followed by overweight (17.6%), obesity (9.3%), thinness (7.9%), and severe thinness (4.1%). The mean PEFR was 204.2±43.3 L/min. PEFR was significantly higher in early adolescents and in boys compared to pre-adolescents and girls (P<0.001). A significant difference was observed in PEFR across BMI categories (P<0.001), with lower values in overweight children. Family history of atopy and pet exposure showed no significant association with PEFR. On multivariable regression analysis, age, male gender, mosquito mat use, and BMI outside the normal range were independently associated with PEFR (P<0.05). Conclusion: PEFR in school-aged children is affected by age, sex, nutritional status, and certain environmental factors. PEFR assessment alongside growth monitoring may help identify variations in lung function in school-aged children.